Rate reducer for a firearm



May 1 4, 1957 D. c. FLETCHER 2,799942 RATE REDUCER FOR A FIREARM Filed Jan. s, 1954 2 sheets-snee*b 1' www@ May 14, 1957 D. c. FLETCHER 2,791,942

RATE REDUCER FOR A FIREARM INVENTOR.

:muaCElE-imher RTTOENEYS RATE REDUCER FOR A FIREARM David C. Fletcher, Springfield, Mass., assigner to the United States of America as represented by the Secretary ot the Army Application January 8, 1954, Serial No. 403,080

4 Claims. (Cl. 89-131) (Granted under Title 35|, U. S. Code (1952), sec. 265) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to automatic firearms, wherein the tiring mechanism is actuated by a reciprocating rod r and which `embodies a sear locked hammer, and is particularly 'directed to a device for reducing the rate of re thereof.

lt has been found in lirearms of automatic type, especially in shoulder arms, that the rate of tire is oftentimes more rapid than is necessary, causing unnecessary waste of ammunition. Another undesirable result is that the shooter lhas diculty :in maintaining the -aim of the weapon, sothe effectiveness thereof is considerably decreased. Further, the weapon is caused to heat up too rapidly, resulting in damage to the barrel, and the moving parts to become unduly worn.

lt is, therefore, the object of this invention to provide in an automatic firearm means for introducing a lapse of time between successive shots.

It is a speciiic object of this invention to provide in the firing mechanism of an automatic weapon a rotary inertia member which introduces an adjustable interval of time between successive shots.

It is another speciic object of this invention to provide in an automatic firearm a trigger mechanism wherein a spring-energized ywheel is used to unlock a springbiased member arranged to actuate the sear mechanism, the time consumed in the loading of the spring and the subsequent energizing of the ywheel thereby introducing L a delay between successive shots.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred Iembodiment as shown in the accompanying drawings in which:

Fig. 1 is a longitudinal cross-sectional view of the left side of a firearm showing the trigger mechanism with the hammer in cocked position, the lirearm bolt moved away from recoil position going toward battery position and the sear actuator lock holding the sear actuator in retracted position;

Fig. 2 is similar to Fig. l but showing the trigger mechanism immediately after the scar actuator lock has unlocked the sear actuator which has been biased forwardly to trip the secondary sear for release of the hammer;

Fig. 3 is an enlarged lateral cross-sectional front view of the trigger mechanism showing the relationship of the parts when the flywheel spring has been completely energized by recoil of the firearm bolt and the ywheel is stopped from further rotation by the Geneva stop work device;

Fig. 4 is similar to Fig. 3 but showing the Geneva stop work device engaged by the flywheel rotary inertia member after one revolution;

Fig. 5 is similar to Figs. 3 and 4 but showing the ywheel stopped from further rotation by the Geneva stop States Patent i diameter through tiywheel 33.

Y 2,791,942 Patented may is, i957 work device after completing one revolution and the energy of the flywheel has been imparted to the sear actuator lock for rotation thereof to unlock the sear actuator; and

Fig. 6 is an exploded right side view of the trigger mechanism.

Shown in the figures is the ring mechanism of a lirearm of the type of the U. S. rifle, cal. .30 Ml which has been adapted by the device of this invention to tire automatically at a retarded rate. Included in the ring mechanism is a conventional trigger housing 9 and mounted for pivotal movement therein is a hammer 12 having an extending hammer arm 19. Hammer 12 is biased to a firing position by a spring 13 and is arranged to be ice v actuated to a cocked position by the engagement of a bolt 14 during recoil flight. Hammer 12 is held releasably in the cocked position by a pivoted sear device 15. Sear device 15 includes a primary sear 16 Which is integral with a trigger 17 and which is arranged to engage a lug 18 on the forward side of hammer arm 19 for releasably holding hammer 12 in the cocked position when the trigger is in a forward position. A conventional secondary sear 2li is pivotally mounted to primary sear 16 and is arranged to engage a lug 21 on the rearward side of hammer arm 19 for releasably holding hammer 12 when `trigger 17 is in a retracted position yand to deliver hammer 12 into releasable engagement With primary sear 16 when trigger 17 is permitted to return to the forward position. ln addition, there is provided on secondary sear 2i) an arm portion 22 which extends rearwardly from the base thereof and which, when pressed downwardly, actuates such secondary scar to release hammer 12.

As is well-known, trigger housing 9 is provided with spaced longitudinal weils 23. Traversing the rearward portion of the right one of walls 23 is a cylindrical hole 24 which receives a spindle member 25. Spindle 25 is comprised of an externally threaded shank potrion V26, receivable by hole 24, and a cylindrical basal portion 27 of larger diameter, and is provided with an axial passageway 28 therethrough. Spindle 25 is mounted in hole 24S so that basal portion 27 is located between walls 23 and a nut 29 is threadably mounted on the potrion of shank 26 that extends outside the right one of the walls for securing such spindle against displacement. A screw driver slot 63 is provided in the free end of shank 26.

Fixed to basal portion 27 is the inner end of a coplanar spiral spring 31 which terminates at the other end in Kan outwardly extending lock portion 32 and which is arranged to be wound by the counterclockwise rotation (referring to Fig. 6) of such extending lock portion. Mounted for rotary movement on spindle 25 is a iiywheel 33 having a concentric annular groove 34 which forms a hub portion 35, Areceivable in a mating recess 30 in spindle 25, and a rim portion 36. A slit S is arranged in rim portion 36 so as to receive lock portion 32 of spring 31 whereby the aforementioned counterclockwise rotation of ilywheel 33 winds such spring .around basal portion 27. The circumference of ywheel 33 is stepped down to a reduced diameter portion ifi on the side opposite groove 3d and formed thereby is a vertical annular surface 6i). Mounted radially in reduced diameter portion d4 so as to extend outwardly therefrom is a pin 4S.

A transverse hole 3S is provided in the left one of walls 23 in alignment with an axial bore 39 of smaller Extending into trigger housing 9 through hole 355 is an axle member d1. Axle 41 is provided with a diametrically reduced cylindrical end portion 42, which is receivable in bore 39 to provide rotary support for flywheel 33, :and an adjacent cylindrical portion 43 snugly receivable by hole 33. The junction of cylindrical portions 42 and 43 forms an annular shoulder 47 which engages the side of flywheel 33 to hold hub portion 35 thereof in recess 30 and which i-s so arranged that pontion 43 of axle 41 extends outwardly from the left one of the walls 23. Fixed to such extending portion is the inner end of a coplanar spiral spring 458 which is wound by counterclockwise rotation (referring to Fig. 6) of axle 41. The free end of spring 48 is provided with an arcuate portion 49 which partially surrounds a pin 73 extending outwardly from the associated one of the walls 23 to anchor such end during rotation of axle 41.

Fixedly mounted on cylindrical portion 43 of axle 41, as by press fit, is a sear actuator lock member t) substantially of rectangular cross section. The front side of the left one of the walls 23 is formed arcuately around hole 3S so as to be concentric therewith and the end of sear actuator lock 50 mounted on axle 4l is reduced to permit an arm portion 51 formed thereby to be received between flywheel 33 and such `one of the walls 23, permitting pivotal movement of the sear actuator lock be tween a forward horizontal position and an upward vertical position. an integral catch 54 extends longitudinally from the mounted end of sear actuator lock 50 and extending inwardly from the free end of such sear actuator lock is a longitudinal cylindrical passageway 52 which is transversed by a bore 53. Mounted in passageway 52 for cooperation with flywheel 33 is a Geneva stop work device 55. Geneva stop work device .55 is provided with a stat portion 56 which is rotatably mounted in passageway 52, and a pin 57 installed in bore 53 cooperates with an annular indent 5S in such staff to rotatably secure such Geneva stop work device in sear actuator lock 50. Fixed to the free end of staff 56 is a substantially square stop portion 59. The sides of stop portion 59 are arranged to cooperate with planar surface 60 to prevent Geneva stop work device 55 from being turned except as hereinafter noted. Provided yin one of the corners of stop 59 which are adjacent planar surface 60 is lan arcuate recess 61 adapted to receive pin 45. Because the corner of stop 59 is removed by recess 61 clearance is provided for the rotation of such stop 90. Therefore, through the cooperation of pin 45 with recess 61 during rotation of flywheel 33, Geneva stop work device 55 is oscillatable 90 between the engagements of the sides of the stop por- `tion adjacent recess 61 with planar surface 60 as best shown in Figs. 3, 4 and 5.

Provided in the lower rear portions of walls 23 is a pair of aligned holes 64 which receive a pin 62. Pivotally mounted on pin 62 is a sear actuator 65 which occupies a position between flywheel 33 and the right one of the walls 23 as best shown in Figs. 3, 4 and 5. A double arm coil spring 66 is also mounted on pin 62 between the left one of the walls 23 and Sear actuator 65 and is arranged to maintain -sear actuator 65 in lateral position `on the pin. The arms of spring 66 engage Sear actuator 65 and trigger housing 9 to bias the scar actuator in a counterclockwise direction, as best shown by Figs. l and 2, to an actuated position. Sear actuator 65 is comprised of a Vertical lever portion 6'7, which extends upwardly from pin 62 between the rearward ends of the walls 23, and an arcuate arm portion 63 which extend-s forwardly and upwardly to be engageable with Sear actuator lock 50, during clockwise rotation, referring to Figs. l and 2, and with arm 22 on secondary scar 20 during counterclockwise rotation. Provided in the upper portion of lever portion 67 is an elongated, arcuately formed slot 69 which cooperates with a cylindrical rod 70 mounted transversely through walls 23 for limiting the pivotal movement of sear actuator 65 between `a rearward retraoted and a forward actuating position. A striker portion 71 extends upwardly from lever portion 67 and is arranged to be engageable by bolt 14 when adjacent recoil position. Provided in the front side of lever portion 67 is a notch 72 arranged to receive catch 54 when sear actuator lock 50 is adjacent the vertical position and sear actuator 65 is adjacent the retracted position. The bias- 4 ing of spring 66 against sear actuator 65 cammingly holds catch 54 in notch 72 after being received therein.

When the weapon, in which the tiring mechanism of this invention is incorporated, is in battery and trigger 17 is in forward position, hammer 12 is engaged in cocked position by primary sear 16, scar actuator 65 is biased by spring 66 to retracted position and sear actuator lock 50 is in horizontal position. Also, flywheel 33 is rotated by spring 31 so that pin 45 engages the top side of stop portion 59 and recess 61 is positioned oppositely from the pin and adjacent planar surface 60, as best shown in Fig. 5, whereby such flywheel is held against rotation by such stop portion which in turn is held against rotation by the engagement thereof with planar surface 60.

Operation To fire the weapon, trigger 17 is pulled rearwardly releasing hammcr 12 which is rotated by spring i3 to tire the Ychambered cartridge. During the ensuing recoil of bolt lili', hammer 12 is cammingly retracted thereby to cocked position and striker portion 71 of Sear actuator 65 is struck by the bolt when adjacent recoil position. The blow against striker 71 causes sear actuator 65 to pivot on pin 62 from actuating toY retreated position whereby arm portion 68 thereof acts against sear actuator lock 50 which is pivoted thereby to the vertical position. As stop portion 59 is immovably engaged with pin 45, the rotation of scar actuator lock 50 thereagainst energizes flywheel 33, winding spring 31 during the resulting clockwise rotation, referring to Fig. 1, of such flywheel.

During the counter-recoil of bolt 12, sear actuator 65, which has been held momentarily retracted through the engagement with bolt 14, is biased in a countcrclockwise direction, referring to Figs. l and 2, by spring 66 until stopped by catch 54 or scar actuator lock 50 being received by notch 72 in such sear actuator lock. While sear actuator 65 was held retracted by bolt 12, such scar actuator lock was held by spring 48 so that catch 54 was ready to be received by notch 72. In the meantime, flywheel 33 has been rotating clockwise, referring to Figs. l and 2, winding spring 31. After one rotation of flywheel 33, pin 45 enters recess 61 in stop portion 59, as shown in Fig. 4, which is rotated thereby until stopped by the engagement of the adjacent side thereof with planar surface 60. At the end of the second rotation pin 45 strikes the blocking side of. stop portion 59, which is now immovable, stopping the rotation of flywheel 33, as shown in Fig. 3. At this time, the energy stored in spring 31 causes counter-rotation of iiywheel 33, referring to Figs. 1 and 2. At the completion of the first counter-rotation of flywheel 33, pin li5 enters recess 60, which was indexed during the preceding rotation, causing stop 59 to rotate 90 until stopped by the engagement of the adjacent side thereof with planar surface 6i). At the completion of the second rotation, pin 45 strikes the blocking side of stop portion 59, which is now immovable, causing sear actuator lock 5t) to be .ipivoted through the transfer of the energy stored in the rotating iiywheel 33 thereto. The pivoting of scar actuator lock 50 moves catch 54 out of notch 72 unlocking sear actuator 5t) which is pivoted in a counterclockwise direction, referring to Figs. l and 2, to actuating position by the bias of spring 66, causing arm 68 thereon to strike arm 22 of secondamI sear 20. As has hereinbefore been explained, when trigger 17 is pulled rearwardly for automatic fire, hammer 12 is releasably engaged in cocked position by secondary sear 2t?. Therefore, when sear actuator 65 strikes arm portion 22, secondary sear 2t? is pivoted, releasing hammer l2 to tire another rount. It is obvious that the time consumed in the rotation and counter-rotation of tiywheel'33 introduces a delay between the tiring of rounds. To adjust the interval between rounds, nut 29 is loosened on spindle 25 which may then be turned by the use of a screw driver in slot 63. Tightening Vor loosening the tension of spring 31, increases or decreases the speed of rotation of flywheel 33 and thereby adjusts the rate of fire. Moreover, if a still longer interval of time is desired, another recess similar to recess 6l may be provided in stop portion 59 whereby three clockwise rotations of flywheel 33 are made before stopped and three counterclockwise rotations made before sear actuator lock 50 is actuated.

It is obvious from the foregoing that there is here provided a novel rate reducer device for a rearm which is simple in design, positive in operation and is easily manuactured.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

l. In a firearm, a reciprocal bolt, a spring-biased hammer actuatable by said bolt from a iiring to a cocked position, sear means for releasably holding said hammer in said cocked position, a pivotal member engageable with said Sear, a spring associated with said pivotal member for actuation thereof against said scar for release of said hammer, said pivotal member being arranged for rotation by said bolt against the bias of said spring to a retracted position, lock means for releasably holding said pivotal member in said retracted position, a rotary inertia member, a spiral spring arranged to be energized by said inertia member and to energize said inertia member in return, means arranged in cooperation with said lock means and said pivotal member for rotating said inertia member a predetermined number of revolutions during actuation of said pivotal member by said bolt to energize said spiral spring, and said inertia member being arranged in cooperation with said means whereby said lock means is actuatable by said inertia member to release said pivotal member for actuation of said sear after said predetermined member of revolutions in the opposite direction when energized by said spiral spring.

2. In a irearm, a reciprocal bolt, a spring-biased hammer actuatable by said bolt from a firing to a cocked position, sear means for releasably holding said hammer in said cocked position, a pivotal member engageable with said sear, a spring associated with said pivotal member for actuation thereof against said sear for release of said hammer, said pivotal member being arranged for rotation by said bolt against the bias of said spring to a retracted position, lock means for releasably holding said pivotal member in said retracted position, a rotary inertia member, a spiral spring arranged to be energized by said inertia member and to energize said inertia member in return, said lock means and said pivotal member being cooperable with said inertia member for rotation thereof to energize said spiral spring when said pivotal member is rotated by said bolt, and a Geneva stop work device to stop the rotation of said inertia member after completing a predetermined number of revolutions and to permit said spiral spring in return to energize said inertia member by such predetermined number of revolutions thereof, said Geneva stop work device being cooperable with said inertia member for transferring the energy of said inertia member to said lock means for actuation thereof whereby said pivotal member is released to actuate said sear means.

3. In a firearm, a reciprocal bolt, a spring-biased hammer actuatable by said bolt from a tiring to a cocked position, sear means for releasably holding said hammer in said cocked position, a pivotal member engageable with said sear, a spring associated with said pivotal member for actuation thereof against said sear for release of said hammer, said pivotal member being arranged for rotation by said bolt against the bias of said spring to a retracted position, lock means for releasably holding said pivotal member in said retracted position, a rotary inertia member, a spiral spring Iarranged to be energized by said inertia member and to energize said inertia member in return, a stop work device cooperating with said lock means jand said pivotal member to rotate said inertia member for energizing said spiral spring when said pivotal member is rotated by said bolt, said stop work device being arranged to stop the rotation of said inertia member after completing a predetermined number of revolutions and to permit said spiral spring in return to energize said inertia member by such predetermined number of revolutions thereof, said stop work device being arranged to transfer the energy imparted to said inertia member by said spiral spring to said lock means whereby said pivotal member is released to actuate said sear means, and means for adjusting the preload of said spiral spring whereby the revolutions per minute of said inertia member while energizing said spiral spring and being energized thereby may be increased or decreased.

In :a rearm, a bolt reciprocable between a battery and a recoil position, a spring-biased hammer actuatable by said bolt from a tiring to a cocked position, sear means for releasably holding said hammer in said cocked position, a pivotally mounted |actuator member having an arm portion engageable by said bolt when adjacent said recoil position for rotation of said actuator member to a retracted position and a lever portion engageable with said sear means for actuation thereof during counter-rotation of said actuator member, a spring for biasing said actuator member against said sear means for actuation thereof, a pivotal lock member actuatable by said lever portion to a locked position during said rotation of said actuator member, resilient means for holding said lock member in said locked position while said arm portion is in engagement with said bolt, said lock member being cooperable with said lactuator member for releasably holding thereof in said retracted position, a Geneva stop work device mounted to said lock member, a rotary inertia member having a radially mounted pin arranged for cooperation with said Geneva stop work device whereby rotation of said lock member by said actuator member energizes said inertia member during movement of said actuator member to said retracted position and permits a predetermined number of revolutions of said inertia members before being stopped, a spiral spring arranged to be energized by said inertia member when rotated by said |actuator member and to energize said inertia member in return after being stopped by such Geneva stop work device, said Geneva stop work device being arranged to transfer the energy of said inertia member to said lock member after completion of said predetermined number of revolutions wherby said lock member is rotated to unlock said actuator member for lactuation of said sear means, and means for adjusting the tension of said spiral spring whereby the revolutions per minute of said inertia member may be increased or decreased.

References Cited in the iile of this patent UNITED STATES PATENTS 1,431,057 Sutter Oct. 3, 1922 1,573,655 Sutter Feb. 16, 1926 2,154,770 Potter Apr. 18, 1939 FOREIGN PATENTS 684,426 Germany Nov. 24, 1939 

